EP 0,898,890 describes an extrusion die for producing a product that has the overall shape of a nucleus surrounded by a ring. The product is obtained by extruding a single substance through a die having a feed orifice plate that opens into an extrusion chamber that is divided into two concentric chambers by a separating cone. The position of the cone can be adjusted relative to the outer casing of the die. This adjusts the relative size of the extrusion openings and hence the size of the nucleus and outer ring.
U.S. Pat. No. 2,858,218 describes a cereal in the form of flakes which has a relief comparable to the surface of a raspberry, and a method for obtaining such a cereal. The method involves cooking a mixture of cereal and water at atmospheric pressure, extruding the resulting cooked paste, using a piston to drive the cooked paste through a die having a number of holes to form parallel filaments of the cooked paste, combining the filaments, laterally compressing the bundle in a tubular extension of the die so that filaments stick together and form a cylinder, drying the cylinder, cutting the cylinder transversely into thin slices, and causing the slices to swell under the action of heat.
U.S. Pat. No. 3,482,992 describes a cereal in the form of flakes made up of touching pieces, the intersection where the pieces meet being colored, and a method for obtaining such a cereal. The method involves cooking a mixture of cereal and water in a cooking device to provide a cooked paste; extruding the cooked paste through a die which has a number of circular outlet orifices, in particular six holes arranged in a circle around a central hole; and injecting a colorant through small intermediate holes to form parallel strands of cooked paste which are colored at their interface. The strands are combined into a bundle and compressed laterally in a tubular extension of the die so that they stick together and form a composite strand. The diameter of the strand is then reduced by drawing it longitudinally and the strand is cut transversely into thin slices. The slices are dried and made to swell under the action of heat.
The object of the present invention is to provide an extrusion die that makes it possible to produce an expanded cereal with a particularly attractive three-dimensional shape, the three-dimensional shape being an array of touching balls.